Laminates of thermoplastic fluororesins and their manufacture

ABSTRACT

A laminated product, in particular a fuel hose, comprises a fluororesin layer and, superimposed on the fluororesin layer, a layer of cured rubber obtained or obtainable by curing a rubber composition comprising a blend of 60 to 95 wt % highly-saturated nitrile copolymer rubber with 40 to 5 wt % epihalohydrin rubber. The rubber blend layer can be made to adhere well to the fluororesin layer by curing it in situ. The nitrile rubber component confers heat resistance on the rubber layer while adhesion is maintained.

This invention relates to laminated products comprising a layer ofthermoplastic fluororesin laminated with a rubber layer. It may haveparticular application for fuel hoses, and other practical applicationsin which a combination of oil resistance and flexibility is called for.

BACKGROUND

It is known that thermoplastic fluororesins have excellent oilresistance and are therefore useful as a material in fuel hoses forautomobiles and aircraft. However fluororesins are poor in flexionproperties in that they are liable to fatigue, leading to rupture. Forthis reason fluororesins are not used alone to make fuel hoses. Rather,an epichlorohydrin rubber or ethylene-acrylate rubber is used to providean outer layer for the hose, with the fluororesin as an inner layer.

In recent years there has been increasing demand for fuel hoses withbetter heat resistance. Ethylene acrylate rubbers have generally goodheat resistance. But, their oil/fuel resistance is poor leading todanger if the inner fluororesin layer ruptures. Epichlorohydrin rubbersare better in this respect, but their heat resistance is poor.

OBJECTS OF THE INVENTION

It is desired to provide new and useful laminated products comprising afluororesin layer and a cured rubber layer, in which oil resistance canbe combined with one or more and preferably all of flexibility, weatherresistance and heat resistance. Another aspect of the present aims is toprovide a method of making such laminated products. More specificaspects are a fuel hose or other fuel- or oil-retainment article madefrom or comprising such a laminate, and a method of making such a hoseor other article.

THE INVENTION

The inventor has conducted extensive researches and has found that arubber composition which is a blend of highly-saturated nitrilegroup-containing rubber and epihalohydrin rubber can give a goodcombination of oil resistance, flexibility and heat and weatherresistance. Furthermore, by contacting the fluororesin layer with acurable composition blend of the above-mentioned rubbers and curing therubber composition blend in contact with the fluororesin layer, a goodadhesion between the two layers can be achieved.

These are surprising and valuable findings because, althoughhighly-saturated nitrile group-containing copolymer rubbers have goodproperties of oil-resistance, weather resistance and heat resistance ithas not been practical to adhere a highly-saturated nitrilegroup-containing copolymer rubber properly to a fluororesin layer.

A first aspect of the invention provides a laminated product comprisinga fluororesin layer and, superimposed on the fluororesin layer, a layerof cured rubber obtained or obtainable by curing a rubber compositioncomprising a blend of 60 to 95 wt % highly-saturated nitrile copolymerrubber with 40 to 5 wt % epihalohydrin rubber.

The laminated product may feature a contact bond between the fluororesinlayer and cured rubber layer achieved by means of curing the rubberblend composition in contact with the fluororesin layer.

In a particular embodiment the product is a conduit or vessel consistingessentially of or comprising such a laminate, and particularly which isto retain an oil or oil-based fluid such as a fuel. A fuel hose is apreferred embodiment.

A second aspect of the invention is a process for preparing such alaminated product, comprising contacting a layer of thermoplasticfluororesin with a layer of rubber blend composition as specifiedherein, and curing the rubber composition to form a cured rubber layerbonded directly to the fluororesin layer.

FURTHER DETAILS; OPTIONS AND PREFERENCES

Thermoplastic fluororesins usable herein for the fluororesin layer maybe of a type already familiar to the skilled person and can be selectedin accordance with conventional practice.

In general such resins feature a fluorinated hydrocarbon main chain. Thefluororesin melting point is preferably at least 100° C., morepreferably at least 110° C., more preferably 120° C. It is preferablynot more than (up to) 320°, more preferably 250° C., more preferably175° C. Melt flow index measured at 265° C./5 kg is preferably at least5, preferably not more than 60.

The thermoplastic fluororesin preferably has more than 50 wt % monomerresidues selected from vinylidene fluoride, hexafluoropropylene andtetrafluoroethylene units. Examples of suitable fluororesins includeterpolymers of vinylidene fluoride, hexafluoropropylene andtetrafluoroethylene, copolymers of ethylene and tetrafluoroethylene,copolymers of hexafluoropropylene and tetrafluorethylene, polyvinylidenefluorides, and polytetrafluoroethylenes. Among these a terpolymer ofvinylidene fluoride, hexafluoropropylene and tetrafluoroethylene ispreferred. Examples of suitable fluororesins on the market includeTHV200, THV410, THV500 and THV500G produced by Dyneon GmbH, andequivalents thereof.

Any suitable preparation process may be used for the fluororesin.Additives which may be conventional, e.g reinforcing agents,antioxidants, other oxidation inhibitors, processing aids and so forthmay be compounded with it according to preference and the particulartechnical demands involved. Other resins may be blended with thefluororesin, especially in minor quantities, provided that the desiredfluororesin properties are retained.

In the present invention a particular type of rubber, comprising a blendof nitrile rubber and epichlorohydrin rubber, is laminated with thefluororesin layer.

The nitrile rubber is generally one obtained by copolymerising anα,β-ethylenically unsaturated nitrile monomer with one or more othermonomers, and optionally hydrogenated to achieve a suitable level ofunsaturation depending on the monomers used and the technical demands onthe product.

The nitrile monomer may be selected in accordance with conventionalpractice. Suitable examples include acrylonitrile, methacrylonitrile andα-chloro-acrylonitrile, with acrylonitrile being preferred. The contentof nitrile monomer residues in the rubber is preferably at least 10 wt%, more preferably 13 wt %, most preferably 15 wt %. Preferably it isnot more than (up to) 70 wt %, more preferably 60 wt %, most preferably50 wt %.

The monomer to be copolymerised with the nitrile monomer can be selectedin accordance with conventional practice for nitrile rubbers. One ormore may be selected from conjugated diene-monomers, other dienemonomers, α-olefins and other copolymerisable monomers.

When conjugated diene is used the content of residues thereof in thecopolymer is preferably at least 30, more preferably at least 40 andmost preferably at least 50 wt %. Preferably it is not more than (up to)90, more preferably 87, most preferably 85 wt %. When using conjugateddiene the rubber thus obtained may have a high iodine value. If theiodine value is too high it may be lowered by hydrogenatingcarbon-carbon double bonds in the copolymer, using conventionalhydrogenation.

Examples of suitable conjugated dienes include 1,3-butadiene, isoprene,2,3-dimethyl-1,3-butadiene and 1,3-pentadiene. 1,3-butadiene ispreferred.

Among other dienes, those having from 5 to 12 carbon atoms arepreferred. Suitable examples include 1,4-hexadiene and 1,4-pentadiene.

Among α-olefins, those having from 2 to 12 carbon atoms are preferred.Suitable examples include ethylene, propylene, 1-butene,4-methyl-1-pentene, 1-hexene and 1-octene.

Examples of other monomers capable of copolymerising with nitrilemonomers include ethylenically-unsaturated carboxylic acid estermonomers, aromatic vinyl monomers, fluoroalkyl-containing vinylmonomers, ethylenically-unsaturated monocarboxylic acids and the like.

The Mooney viscosity (ML₁₊₄, 100° C.) of the nitrile rubber ispreferably at least 15, more preferably at least 30 and most preferablyat least 45. It is preferably not more than (up to) 200, more preferablyup to 150, most preferably up to 100. If the Mooney viscosity is verylow the strength of the product may be undesirably reduced, whereas ifit is very high the processability of the rubber composition isaffected.

In general the nitrile rubber should be highly saturated to avoidundesirable heat aging in air. Thus the iodine value of the rubber ispreferably not more than 120, more preferably not more than 60, and mostpreferably not more than 30.

Epihalohydrin rubbers, particularly epichlorohydrin rubbers, are inthemselves well-known. Generally speaking they are polymers obtained byring-opening polymerisation of epihalohydrin monomer, either alone or asa copolymer with a copolymerisable monomer.

The Mooney viscosity (ML1+4, 100° C.) of the epihalohydrin rubber usedherein is preferably at least 20, more preferably at least 30, mostpreferably at least 35. If the Mooney viscosity is very low retention ofshape during rubber processing is sometimes insufficient and the rubbercompound may become too tacky. The Mooney viscosity is preferably notmore than (up to) 150, more preferably up to 120, most preferably up to100. If it is very high the flow of the compound during rubberprocessing may be poor and dimensional stability is sometimes reduced.

Suitable epihalohydrin monomers include epichlorohydrin, epibromohydrinand β-methyl-epichlorohydrin. Epichlorohydrin is preferred. The contentof epihalohydrin monomer residues in the epihalohydrin rubber ispreferably at least 20 mol %, more preferably at least 30 mol %. If themole content of epihalohydrin monomer residues is very low the curedrubber tends to be rather hygroscopic. The epihalohydrin residue contentis preferably not more than (up to) content is very high the coldresistance of the cured rubber may be adversely affected.

Alkylene oxide monomers are preferable as monomers copolymerisable withepihalohydrin monomer. The monomer is ethylene oxide, or a compound inwhich at least one of the hydrogen atoms of the ethylene oxide structureis substituted by a saturated hydrocarbon group. The substituting groupmay be a halogen-containing group. Suitable examples include ethyleneoxide, propylene oxide, 1,2-epoxybutane, 2,3-epoxybutane,1,2-epoxyhexane, 1,2-epoxy-isobutane, 1,2-epoxy-3-methylpentane,1,2-epoxycyclopentane, 1,2-epoxycyclohexane,2,3-epoxy-3-chloromethyl-butane and 1,2-epoxy-4-chloropentane. Ethyleneoxide and-propylene oxide are preferred.

The content of alkylene oxide residues in the epihalohydrin rubber ispreferably at least 10, more preferably at least 20 mol %. If the molecontent of alkylene oxide residues is very low the cold resistance ofthe cured rubber tends to be poor. This content is preferably not morethan (up to) 80 mol %, more preferably not more than 70 mol %. If isvery high the product tends to foam during processing and thehygroscopic property of the cured rubber is sometimes high, leading insome cases to difficulties in using the product depending on theprocessing and usage conditions.

An ethylenically-unsaturated monomer which is copolymerisable in thering-opening copolymerisation with the epihalohydrin monomer and theoptional alkylene oxide monomer can be used. Suitable examples includevinyl glycidyl ether, allyl glycidyl ether, glycidyl acrylate, glycidylmethacrylate, vinyl cyclohexyl ether and 3,4-epoxy-1-butene. Allylglycidyl ether, leading to cured products of excellent ozone resistance,is preferable. The content of residues of such other monomer in theepihalohydrin rubber is preferably not larger than 15 mol %, morepreferably not larger than 12 mol % and most preferably not larger than10 mol %. If the content of such other monomer is too large, the“elongation at break” of the cured product may be low.

The combination of these rubbers used in the present invention comprisesfrom 60 to 95 wt %, preferably from 65 to 93 wt % of the highlysaturated nitrile rubber and from 40 to 5 wt %, preferably from 35 to 7wt %, of the epihalohydrin rubber. If the content of the nitrile rubberis too small, fuel-transmissibility through the rubber layer isexcessive if the fluororesin layer ruptures. If the nitrile rubbercontent is too large, adhesion between the fluororesin layer and thecured rubber layer tends to be weak.

The rubber in the curable rubber composition may consist entirely oressentially of the two above-specified rubber types. However it ispossible to include a proportion—typically a minor proportion—of otherrubber provided that adequate properties are maintained, in which casethe % ge values specified above are to be interpreted as relative partsby weight out of 100 parts of the two rubber types.

The rubber composition is rendered curable by the inclusion of curingagent. The curing agent used is not particularly limited, but an organicperoxide curing agent is preferable. Examples of suitable organicperoxide curing agents include dicumyl peroxide, tert-butyl cumylperoxide and 1,3-bis(tert-butylperoxy isopropyl) benzene. The amount ofthe organic peroxide curing agent is not particularly limited, but ispreferably in the range of 0.1 to 15 parts by weight, more preferably0.5 to 12 parts by weight, based on 160 parts by weight of the rubbercomponents in the rubber composition.

It is preferred that an acid receiver, such as are generally used as acompounding agent in epihalohydrin rubbers, is included in the rubbercomposition. Suitable acid receivers include oxides, hydroxides andcarbonates of alkali,metals and alkaline earth metals. Specific examplesinclude magnesium oxide, calcium oxide, zinc oxide, sodium hydroxide,calcium hydroxide, magnesium hydroxide and sodium carbonate. The amountof acid receiver is preferably in the range of 0.5 to 5 parts by weight,more preferably 1 to 3 parts by weight based on 100 parts by weight ofthe rubber components of the rubber composition. Inclusion of an acidreceiver can promote adhesion between the fluororesin layer and thecured rubber layer, but if the amount of acid receiver is too large thecured rubber layer tends to be weakened.

The rubber composition may contain any suitable additives such as resin,reinforcing agent, curing aid, curing accelerator, oil, plasticiser,antioxidant, oxidation inhibitor, light stabiliser, processing aid,anti-friction additive, adhesive, lubricant, flame retarder, mildewcide,antistatic agent and colorant if desired.

The method of formation of the fluororesin and rubber composition layersis not particularly limited but extrusion moulding is preferable,especially when making a fuel hose having the fluororesin layer as aninner layer and the cured rubber layer as an outer layer.

The preparation of a laminate wherein the fluororesin layer and therubber layer are firmly adhered by disposing the fluororesin in contactwith the layer of the rubber composition, and curing the rubbercomposition to form a cured rubber layer with the fluororesin layer andthe cured rubber layer adhered at the interface.

The method for achieving curing-adhesion at the interface is notparticularly limited. Conventional methods used for achieving orenhancing the curing-adhesion between fluororesin and epihalohydrinrubber can be employed.

Thus it is preferable to use an organic phosphonium salt at theinterface between the fluororesin layer and the rubber compositionlayer.

The organic phosphonium salt is a compound as follows:PR¹R²R³R⁴Xwherein R¹, R², R³ and R⁴ each represent a hydrocarbon group which mayhave a substituent and X represents a univalent minus ion. Among these,compounds of the following formula are preferred:

wherein R⁵, R⁶, R⁷ and R⁸ may each represent a hydrocarbon group having1 to 20 carbon atoms which may have a substituent, while no more thanthree of R⁵, R⁶, R⁷ and R⁸ may be primary, secondary or tertiary aminogroups or fluoroalkyl, and R⁹ represents hydrogen or an alkyl grouphaving 1 to 20 carbon atoms. Examples of the organic phosphonium saltinclude tetrabutylphosphonium benzotriazolate, tetraoctylphosphoniumbenzotriazolate, methyltrioctylphosphonium benzotriazolate,tetrabutylphosphonium tolyltriazolate and tetraoctylphosphoniumtolyltriazolate.

The method of using the organic phosphonium salt is not particularlylimited. Suitable methods include compounding it into the fluororesinand/or the rubber composition, or coating it on the surface of thefluororesin layer which is in contact with the rubber composition layerand/or on the surface of the rubber composition layer which is incontact with the fluororesin layer. Compounding into the rubbercomposition is preferable.

When the organic phosphonium salt is compounded into the the rubbercomposition, the amount of the organic phosphonium salt is preferably inthe range of 0.5 to 10 parts by weight, more preferably 1 to 5 parts byweight and most preferably 1.5 to 3 parts by weight based on 100 partsby weight of the rubber components of the rubber composition.

When the organic phosphonium salt is coated on a contact surface, theorganic phosphonium salt may be dissolved or dispersed in an organicsolvent and coated e.g. by spraying or brush-coating. Suitable organicsolvents include acetone, methyl ethyl ketone, methyl alcohol, ethylalcohol, benzene, toluene and xylene. The concentration of the solutionor dispersion is preferably in the range 5 to 20 wt % for ease ofcoating and rate of evaporation of the solvent.

It is preferable to use a bisphenol at the contact interface between thefluororesin layer and the rubber composition layer. This is a compoundhaving a carbon atom bonded with two phenols. Examples include bisphenolAF, bisphenol F, bisphenol A, 3,3′-tetrachloro-bisphenol A, bisphenol S,5,5′-tetrabromo-bisphenol S, hydrogenated bisphenol A and4,4′-bis-sulfonylphenol. 4,4′-bis-sulfonylphenol is preferred.

The method of using the bisphenol is not particularly limited. They maybe compounded into the fluororesin and/or the rubber composition, orcoated on the surface of the fluororesin layer which is in contact withthe rubber composition layer and/or on the surface of the rubbercomposition layer which is in contact with the fluororesin layer.Compounding into the rubber composition is preferable.

When bisphenol is compounded into the the rubber composition, the amountof bisphenol is preferably in the range of 0.05 to 2 parts by weight,more preferably 0.1 to 1.5 parts by weight and most preferably 0.2 to 1parts by weight based on 100 parts by weight of the rubber components ofthe rubber composition.

The method of curing the rubber composition layer is not particularlylimited, and may be appropriately chosen from conventional heatingmethods such as press heating, steam heating, oven heating, hot-airheating, infrared radiation heating and microwave heating. The heatingtemperature and curing time are not particularly limited. Heatingtemperature is preferably in the range 130 to 200° C., more preferably140 to 180°. Curing time is preferably from 1 to 15 minutes. These canbe determined using the skilled person's expertise.

The thicknesses of the respective layers in the laminate may bedetermined in accordance with conventional practice and/or routinetesting for the intended purpose. The laminate preferably consists ofthe two mentioned layers, although the presence of one or more furtherlayers is not ruled out.

EXAMPLES

The invention is now illustrated by means of the following examples.Note: all parts and % are by weight unless otherwise specified.

Tests used in the Examples were as follows.

Tensile strength, elongation and tensile stress at 100% elongation of,the cured rubber were measured according to JIS K6251. Hardness wasmeasured using a JIS type A spring hardness tester according to JISK5253.

Compression set was measured after a moulded specimen had beenmaintained at a temperature of 150° C. for 70 hours, according to JISK6254.

Characteristics of cured rubber after a specimen of cured rubber wasmaintained at a temperature of 150° C. for 70 hours were measured by thesame method as described above.

The volume change and changes in other properties were measured after aspecimen of rubber was maintained in diesel fuel oil at 60° C. for 70hours.

To evaluate the adhesion between the fluororesin layer and the layer ofcured rubber, peel-off strength was measured at a peel-off rate of 50mm/min. according to JIS K6256. A proportion of rubber-sticking wasmeasured by observing the peeled-off surface of the fluororesin layerafter the peel-off test, measuring the area of residual stuck rubber onthe fluororesin surface, and expressing this as a percentage of thetotal area of the peeled surface.

Example 1

The following ingredients were mixed using a open-roll at a temperatureof 50° C. to prepare a curable rubber composition. Each measurement wascarried out using the curable rubber composition. The results are shownin Table 1.

-   -   90 parts by weight of a hydrogenated acrylonitrile-butadiene        copolymer (iodine value: 11; content of acrylonitrile units: 36        wt %; Mooney viscosity (ML1+4, 100° C.): 57);    -   10 parts by weight of epichlorohydrin rubber {content of        epichlorohydrin units:40 mol %, content of ethylene oxide units:        56 mol %, content of allyl glycidyl ether units: 4 mol %, Mooney        viscosity {ML1+4, 100° C.): 60);    -   50 parts by weight of carbon black (FEF I Seast SO (trade mark)        produced by Tokai Carbon);    -   10 parts by weight of plasticiser (tri-n-octyltrimellitate);    -   2 parts by weight antioxidant (50 wt % zinc salt of        2-mercapto-methylbenzimidazole, 50 wt %        4,4′-(α,α′-dimethylbenzyl)diphenylamine);    -   2 parts by weight sodium carbonate;    -   0.5 parts by weight of bisphenol-containing. compound (75 wt %;        bisphenol {4,4′-bis-sulfonylphenol) DYNAMAR FC 5157 produced by        Sartomer Company);    -   2 parts by weight of tetrabutylphosphonium benzotriazolate;    -   12 parts by weight of curing agent {40 wt % organic peroxide        (1,3-bis(tert-butylperoxy isopropyl) benzene): Vul-cup 4OKE        produced by Herculeis Inc.).

The fluororesin used was a terpolymer of vinylidene fluoride,hexafluoropropylene and tetrafluoroethylene, melting point: 162 to 174°C.; melt flow index at 265° C./5 kg: 5 to 15, THV 500G produced byDyneon GmbH. Each of the fluororesin and the curable rubber compositionwas mixed using a six-inch (152 mm) open roll to sheets of uniform 2 mmthickness. Each sheet was cut to a sample of 6×10 cm. The edge part ofeach sample was covered with cellophane paper so that the coveredportion would not adhere to others, and was left to be gripped by achuck in a pee- off test. The fluororesin sample and the curable rubbercomposition sample were laminated, and pressed together under a pressureof 4 MPa at 170° C. for 15 minutes, to form a laminate wherein thefluororesin layer and the cured layer of rubber composition were adheredby curing. The peel-off strength and the proportion of rubber-stickingarea of the laminate were measured. The results are shown in Table 1.

Examples 2-3 and Comparative Examples 1-2

Substantially the same procedure as described in Example 1 was carriedout, except that the contents of hydrogenated acrylonitrile-butadienecopolymer and epichlorohydrin rubber were changed as indicated in Table1, which also shows the test results.

COM- PARATIVE EXAMPLE EXAMPLE 1 2 3 1 2 COMPONENT OF RUBBER COMPOSITION(PARTS BY WEIGHT) Hydrogenated Product of 90 95 70 50 100Acrylonitrile-Butadiene copolymer Epichlorohydrin rubber 10 5 30 50 —Tetrabutylphosphonium 2 2 2 2 2 benzotriazolate Sodium Carbonate 2 2 2 22 Bisphenol-containing compound 0.5 0.5 0.5 0.5 0.5 CHARACTERISTICS OFCURED RUBBER Tensile Strength (MPa) 24.5 26.0 15.0 13.0 20.4 Elongation(%) 190 250 220 240 480 Tensile Stress at 100% 11 13.8 6 4 4 elongation(MPa) Hardness 79 80 75 74 73 Compression Set 32 27 46 70 40 CHANGES OFPROPERTIES UNDER HEAT STABILITY TEST IN AIR Tensile Strength (MPa) 23.324.0 13.0 10.0 18.5 Change rate after test (%) −5.9 −7.7 −13.3 −23.1−9.3 Elongation (%) 180 230 180 180 400 Change rate after test (%) −5.3−8.0 −18.2 −25.0 −16.7 Tensile Stress at 100% 12.3 15.0 8.2 6.2 5.6elongation (MPa) Change rate after test (%) +11.8 +8.7 +36.7 +55.0 +40.0Hardness 81 82 78 80 77 Change volume after test +2 +2 +3 +6 +4 CHANGESOF PROPERTIES UNDER IMMERSION TEST IN FUEL OIL Volume change rate aftertest (%) +18.9 +12.3 +23.6 +38.6 +12.8 Tensile Strength (MPa) 20.2 21.810.8 8.2 17.8 Change rate after test (%) −17.6 −16.2 −28.0 −36.9 −12.7Elongation (%) 180 230 190 160 400 Change rate after-test (%) −5.3 −8.0−13.6 −33.3 −17.7 Tensile Stress at 100% 9.7 11.8 4.8 2.4 3.2 elongation(MPa) Change rate after test (%) −11.8 −14.5 −20.0 −40.0 −20.0 Hardness70 74 65 58 63 Change volume after test −9 −6 −10 −16 −10 ADHESIONBETWEEN THE FLUORORESIN LAYER AND THE CURED LAYER OF THE RUBBERCOMPOSITION Peel Off Strength (N/25 mm) 200 150 160 180 70 Proportion ofRubber-Sticking (%) 100 80 100 100 40

As can be seen from these comparative results, the laminate productsembodying the invention had a high initial adhesion strength between thefluororesin layer and the cured layer of rubber composition, and a highproportion of rubber-sticking, i.e. the two layers were firmly adheredto one another at the interface by co-curing. The characteristics of thecured rubber composition layers and their changes of properties in theheat stability test in air, as well as in the fuel oil immersion test,were excellent.

By contrast, when the rubber composition having a small content of thehighly saturated nitrile group-containing copolymerised rubber and alarge content of the epichlorohydrin rubber was used, the rubber layerwas expanded by swelling and deteriorated because the layer of curedrubber composition had low heat resistance. Furthermore, when the rubbercomposition without epichlorohydrin rubber was used, the laminate wasliable to peeling because of the low adhesion between the two layers(Comparative Example 2).

1. A laminated product comprising a fluororesin layer of a tempolymer ofvinylidene fluoride, hexafluoropropylene and tetrafluoroethylene and,superimposed on the fluororesin layer, a layer of cured rubber obtainedor obtainable by curing a rubber composition comprising a blend of 60 to95% nitrile copolymer rubber having an iodine value of not more than120, with 40 to 5 wt % epihalohydrin rubber.
 2. A laminated productaccording to claim 1 wherein the nitrile copolymer rubber is ahydrogenated acrylonitrile-butadiene rubber.
 3. A laminated productaccording to claim 1 wherein the epihalohydrin rubber is epichlorohydrinrubber.
 4. A laminated product according to claim 1 wherein the rubbercomposition contains an organic peroxide curing agent.
 5. A laminatedproduct according to claim 4 wherein the rubber composition contains 0.1to 15 parts by weight of the organic peroxide curing agent based on 100parts by weight of the rubber components in the rubber composition.
 6. Alaminated product according to claim 1 wherein the rubber compositioncontains an acid receiver, an organic phosphonium salt and bisphenol. 7.A laminated product according to claim 6 wherein the rubber compositioncontains from 0.5 to 5 parts by weight of acid receiver, 0.5 to 10 partsby weight of the organic phosphonium salt and 0.05 to 2 parts by weightof bisphenol based on 100 parts by weight of the rubber components ofthe rubber composition.
 8. A laminated product according to claim 6wherein the acid receiver is sodium carbonate.
 9. A laminated productaccording to claim 6 wherein the organic phosphonium salt istetrabutylphosphonium benzotriazolate.
 10. A laminated product accordingto claim 6 wherein the bisphenol is 4,4′-bis-sulfonylphenol.
 11. Alaminated product according to claim 1 which is a fuel hose.
 12. Amethod of making a laminated product according to claim 1 comprisingcuring a layer of the rubber composition in contact with thefluoro-resin layer to form a bond between said layers.